Science Fair Project Encyclopedia
There are several types of bicycle lights available. Among cyclists, personal opinions vary widely on what is the best kind of lighting system. In the last ten years, bicycle lighting technology has seen significant improvements, offering cyclists less heavy, brighter, and more reliable systems. Conventional carbon filament bulbs with their low brightness/power and short lifetime have almost disappeared from the North American market.
Many cycle commuters build their own lighting systems with commonly available lamps, batteries, and chargers.
In North America, LED bicycle lighting systems are currently in wide usage, especially in urban areas. Both front and back LED lights are available. These systems offer the following advantages: low cost, long battery life, light weight, easily removable from bike, very long bulb(LED) life, and low maintenance. The have the following disadvantages: less bright than other systems(some newer models are still quite bright), less omnidirectional than other systems(but newer models are changing this). Most use standard batteries in which rechargeable batteries can also be used.
Recently there has been much interest and development in the LED lighting market. The previously common Japanese Nichia LED's are slowly giving way in many applications to the newer, more powerful American Luxeon LED's. Power consumption is an issue, but where maximum brightness is required Luxeon's meet the need. The Cygolite company has come out with two products, the Hi-Flux 200, with rechargeable NiMH battery, and the Hi-Flux 100 with a four-C-cell battery pack, which is as bright as most 10-watt halogen systems, but which has a much longer battery life. Endurance is approximately 6 hours /hi beam, 50 hours/lo beam for the 200, and 25 hours/hi beam, 200 hours/lo beam for the model 100. This far exceeds the endurance of a comparably bright halogen system, and the LED emitters last about 100k hours.
LED systems offer the most potential for technological improvements. Every year these lighting systems get cheaper, brighter, and longer lasting.
Generator systems are widely popular in Europe and many parts of the world, and maintain a small following in North America. In these systems, a permanent magnet generator is driven as the bicycle moves, so no batteries are required. These systems have the following advantages: no need to replace or recharge batteries, lights usually firmly attached to bicycle, brighter than LED systems (often, but not always). They have the following disadvantages: somewhat increased drag, potential to slip in wet weather, occasional bulb replacement (~once/yr), wiring systems require occasional maintenance. The most popular style is a sidewall or bottle generator, which rolls along the side wall of the tire, and has a mechanical system to disengage it from the sidewall when not in use. Second most popular is the hub generator, in which the front hub has the generator built-in. Hub generators offer very low maintenance and long life, but leave some residual drag even when the lights are turned off. Less popular variations of generators also exist: ones in which the generator rolls along the outside of the wheel, with the axis of rotation parallel to the wheel axis, and models that attached to the wheel at the hub.
High Power Systems
Many commuters choose to use high power halogen lights, which operate from a rechargeable battery. These systems offer the following advantages: very bright, quality long-life rechargeable battery. They have the following disadvantages: high cost, usually difficult to remove from bike, battery requires occasional recharging (~once/week), bulb will occasionally blow/burn out (~once/yr).
Another choice for a rear lamp, where flashing lamps are legal, is a xenon strobe , which is less directional than LEDs. This is changing as new omnidirectional bright rear LED lights have come to market.
In discussing bicycle lighting systems, it is important to mention that reflective materials, in the form of reflectors, reflective tape, and reflective and high visibility clothing, are also important in making one visible to automobiles.
Safety and legal concerns
For rear lights, LED flashers are popular in North America, but illegal in most other countries. In the United States, most areas require the use of a white front light, visible from some distance away, and red reflector, also visible some distance away. Accident statistics show that front lights are more critical for safety (need a reference here).
Old bits of junk to be cleaned out later In parts of Europe, low power lights that operate from a dynamo are still popular, but are slowly being replaced by safer, higher power, battery operated halogen lights. Front LED lights used to be useful only for being seen, but newer products project a good beam for illuminating the road.
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